As a wind turbine used for a wind generator, there are known wind turbines in which a pitch angle of a wind turbine blade is fixed and a wind turbine in which the pitch angle is variable.
As a mechanism for changing the pitch angle of the wind turbine blade, there is known a mechanism which converts linear motion of a rod in a hydraulic cylinder into rotation around an axis of the wind turbine blade as described in Patent Citation 1. Further, there is also proposed a mechanism which straightly moves a rod in an axial direction thereof using an electric operating machine, and a wind turbine blade is rotated around an axial direction thereof by the movement as described in Patent Citation 2 or the like.
There is also proposed a mechanism in which a gear is provided around a blade rotating wheel, a pinion gear meshing with the gear is rotated by an electric motor, the blade rotating wheel is rotated and this rotation is converted into rotation around an axis of the wind turbine blade as describe in Patent Citation 3. There is also proposed a mechanism which uses a belt instead of the gear.    Patent Citation 1: Japanese Unexamined Patent Application, Publication No. 2003-148321    Patent Citation 2: Japanese Unexamined Patent Application, Publication No. Sho 63-124874    Patent Citation 3: Japanese Unexamined Patent Application, Publication No. 2003-56448